This application claims the benefit of Korean Patent Application No. 2001-70013, filed Nov. 12, 2001, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an image scanning device, and more particularly, to a method and an apparatus for detecting an error in an image scanning device, determining either the exchange of a light source or the presence of a contaminant in an optical path and then informing of the result of the determination.
2. Description of the Related Art
Generally, an image scanning apparatus is incorporated in a copier, a facsimile machine and a copier-facsimile system. One example of the image scanning apparatus is shown in FIG. 1.
FIG. 1 shows an image scanning apparatus disclosed in U.S. Pat. No. 5,978,614, to Takeuchi, issued Nov. 2, 1999, and FIG. 2 is a flowchart showing a method of measuring a quantity of light of a lamp by using the image scanning apparatus of FIG. 1 and informing of a time for lamp replacement.
Referring to FIG. 1, the image scanning apparatus includes a scanning table unit 11 provided to scan a sheet of document placed on a scanning plate 10, and a document feeding unit 12 automatically feeding a plurality of sheets of documents for an automatic and sequential scanning of the documents. First and second scanning units 13 and 14 are driven within the stand-by position P1, white panel position P2, and first and second scanning start positions P3 and P4. The first and second scanning units 13 and 14 are changed to a standby mode when moving to the standby position P1 by a certain translating means, scan the white panel 15 in the white panel position P2, and scan the document in the first and second scanning positions P3 and P4.
Referring to FIG. 2, in a so-called Flat Bed Scanner (FBS) that performs a scanning operation by using the scanning table unit 11, a controller determines whether a start key is selected from a user""s manipulation of keys in operation S10. If the start key is determined as being selected, the first scanning unit 13 moves to the second scanning position P4 in operation S11. Next, the first scanning unit 13 scans the document while moving to a job completion position P5, and at the same time, the image data obtained upon scanning the document is stored in a storage means in operation S12. Then the first scanning unit 13 moves to the white panel position P2 in operation S13. The white panel 15 is scanned and detected by a charge coupled device (CCD) sensor 17 in operation S14.
The controller determines whether or not white pixels of the image data of the scanned document are less than 90% of a predetermined reference in operation S15. When the white pixels of the image data are greater than 90% of the reference, the controller determines a light source 16 emits light appropriately, and compensates the data stored in S12 and prints an image on the sheets in operation S16. Then the first scanning unit 13 moves to the standby position P1 in operation S17.
When the white pixels of the image data are less than 90% of the reference, the controller determines whether the light source 16 emits the light inappropriately. And in this case, the controller deletes the image data stored in the storage means in operation (step S18). Then the controller indicates through a certain display device a need for a lamp replacement in operation (step S19). Accordingly, the user notices the message in the display and replaces the lamp with a new one so as to maintain the appropriate scanning.
A so-called Automatic Document Feeder (ADF) performs the scanning operation by using the document feeding unit 12, in a similar manner as the scanning operation of the FBS. The only difference between the FBS and the ADF is that the ADF first scans the white panel 15, scans the document, and then compares/determines the white pixels of the image data. This is generally because the white panel 15 is placed between the document scanning positions of the FBS and the ADF.
According to the conventional image scanning apparatus as described above, the controller determines that the light quantity of the lamp is inappropriate if the white pixels of the image data of the scanned white panel are less than 90% of the reference. However, the white pixels are sometimes determined as being less than 90% of the reference when there are contaminants disposed in the optical path having a white panel, a mirror, etc.
If the message for the replacement of the lamp is due to the contaminants contained in the optical path, it would be disadvantageous for the user to buy a new lamp that is not actually required. Also, if there is not a sufficient quantity of light due to the presence of the contaminants, the light quantity will still be insufficient even if the user replaces the lamp with a new one.
Also, even when the light quantity of the lamp drops, if taking into account of the fact that the amplifier could compensate the lamp, the detection of error of the scanning apparatus can hardly be accurate only by comparing and determining the light quantity of the lamp.
The present invention has been made to overcome the problems of the related art, and accordingly, it is an object of the present invention to provide a method of detecting an error in an image scanning device, which is improved so as to distinguish a need for a lamp replacement from a contamination of an optical path, and inform the result of the detection accordingly.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The above and other objects are accomplished by a method of detecting an error in an image scanning device that obtains image data when a document is scanned by using a light beam radiated from a lamp according to the present invention. The method includes a setting operation of obtaining initial reference values of a light quantity of the lamp and storing the obtained initial reference values in a memory, a storing operation of measuring the light quantity of the lamp during use of an image scanning system, obtaining measured values for comparing with the initial reference values, and storing the measured values in the memory, and a comparing/determining operation of determining whether to check a presence of error in the lamp or to check a presence of contaminant in an optical path by comparing the initial reference values with the measured values.
The setting operation includes scanning a white panel, extracting a light quantity from the scanned white panel, calculating a reference value R and an initial average value A from the extracted light quantity of the white panel, storing the calculated reference value R and the initial average value A in the memory, dividing the white panel into a number of pixel divisions n, and calculating initial divisional values B1xcx9cBn of light quantities of the respective pixel divisions and storing the calculated initial divisional values B1xcx9cBn in the memory.
The storing operation includes extracting a light quantity of a white value by scanning a white panel, obtaining measured average value a and a minimum value m of the light quantity from the extracted light quantity of the white value, storing the obtained average value a and the minimum value m in the memory, dividing the white value into divided values of pixel divisions n, and calculating measured divisional values b1xcx9cbn of the light quantity of the respective n pixel divisions n and storing the calculated measured divisional values b1xcx9cbn in the memory.
A first checking operation is further provided in the comparing/determining operation, for checking a presence of abnormality of the lamp when a difference between the initial reference values and the measured values is more than a predetermined reference.
The first checking operation includes searching the pixel divisions n for a pixel division to which the minimum value m falls; determining whether the pixel division having the minimum value m is a first division or a nth division, such as a last division, the first and nth divisions disposed at opposite outside portions of the white panel, comparing and thus determining whether the minimum value m is smaller than the calculated reference value R, when the pixel division having the minimum value m is the first or the nth division, and displaying an urging message for a lamp replacement when the minimum value m is smaller than the reference value R.
A second checking operation is also provided either when the pixel division having the minimum value m is not the first nor the nth division, or when the minimum value m is smaller than the reference value R, wherein the second checking operation includes checking the presence of contaminants in the optical path.
The second checking operation is also provided after the display of the urging message for the lamp replacement, and includes checking the presence of contaminants in the optical path.
The second checking operation includes comparing the initial divisional average values B1xcx9cBn of the light quantity of the respective pixel divisions n with the measured divisional average values b1xcx9cbn of the light quantity of the respective pixel divisions, respectively, determining whether there is a pixel division where a difference between the initial average values B1xcx9cBn and the measured divisional values b1xcx9cbn is greater than a predetermined reference, and displaying a message indicating a contamination of the optical path when there is the pixel division having the difference of the initial divisional values B1xcx9cBn, b1xcx9cbn greater than the predetermined reference.